Most furnaces for heating of particulate materials, particularly elongated furnaces, are generally round in cross-section or have a square cross-section. For externally heated furnaces, especially induction furnaces having a round cross-section, the center is equidistant from all sides of the furnace or from the entire periphery, whereas in a furnace of any other standard cross-section, the center is not equidistant from the entire periphery of the furnace, which causes the furnace to tend to develop cold spots. In a round furnace, the coldest spot is the exact center.
Although applicants are aware of numerous furnace configurations, the invented configuration is believed to be heretofore unknown.